Thanks for this thorough investigation Chris. On Sep 21, 2016 6:18 AM, "Christopher Gray" <[email protected]> wrote:
> I finally had a chance to figure out the discrepancy between radio power > readings in the 2.4 GHz band. I've often heard about people getting > significantly reduced signal when switching from airMAX to ePMP on 2.4 > GHz.. but other people see no difference. In my case, I found a drop of > about 7 dB going from airMAX to ePMP on a particular PTP link with matched > settings running 5 MHz channels, but an increase in throughput (which > really made me want to figure out what was going on). > > Following some early morning testing, it turns out: ePMP is reporting > received power while airMAX is actually reporting receive spectral density > with units dBm/20MHz. > > As a result, if you swap radios from airMAX to ePMP when running 20 MHz > channels, you should little to no change at all. If you are running 10 MHz > channels, however, you should expect about 3 dB reduction in reported > signal, and if running 5 MHz channels, you should see about 6 dB reduction > in reported signal. [If you are running 40 MHz channels, you should see an > increase of about 3 dB, but please don't run 40 MHz channels in 2.4 GHz.] > These reductions are not the result of weaker performance, but simply > different units in the signal bar. > > On a side note relative to poor ePMP performance... ePMP has had a > firmware issue with calculating output power in FCC areas resulting in > lower than allowed power output. I've been questioning them about this, and > they tell me the correct output power calculations should be in the "next > firmware". Once this is fixed, weaker customers should have a better chance > of linking up. > > [Also, I should note the AF-2X radios also report received power like the > ePMP.] > > -Chris >
